V2H with Chinese offgrid inverter

[johu]

Bottom line: a) Touran can supply our apartment and b) inverters without DC/DC stage will rectify back into the battery when being fed with a grid tie inverter.

With Tourans 40 kWh battery, a 1.3 kWp solar array and an average daily consumption of 5 kWh (without the car though) I could go offgrid over summer time. Well, if it weren't for the 3 kW power limit which wouldn't support cooking on more than one plate.

Inverter: https://de.aliexpress.com/item/1005002013462606.html

[celeron55]

Any idea what's the supported DC voltage range of that inverter board?

[johu]

When I took apart the 12V input version the DC bus was regulated to 450V. There is no lower limit, just below 320V you will no longer receive 230V output, obviously.

[PrecisionAnalytic]

Well, if it weren't for the 3 kW power limit which wouldn't support cooking on more than one plate.

I was wondering about increasing the limit by running two or more in parallel. Probably not the best design plan I'm guessing, though not an expert and my background is more pharma QC & AR&D so please clarify if you can please why or why not.

However, when I saved to my Wish List I found this up to 8000W appears similar design version: https://www.aliexpress.us/item/3256804681795451.html?

[johu]

Paralleling is indeed not possible as they are not synchronized. But if you find a larger one the problem is solved. Your link is 404

[johu]

I went offgrid for 24 hours and the car battery went from 73 to 83% because we used less energy than solar provided

[Ev8]

That’s awesome you should produce some control boards for those Chinese inverter stages.

[johu]

Nothing to produce really, this board is the whole thing: https://de.aliexpress.com/item/1005002013462606.html

All I added is an isolated power supply for logic supply (logic is on same potential as power)

[Ev8]

Ok for some reason I was under the impression these were just a power stage and had no logic, Ali express states they need a 16v ac input? Is this a feedback input requiring a transformer from the output?

[johu]

No, that is logic supply. Hence the isolated DC/DC converter. It is designed for AC (as in there is a bridge rectifier) as it is normally tapped off the X to 450V DC/DC that I omitted.

[Ev8]

Well I’m inspired enough to to give similar a go, I’ve ordered one of those Ali express inverters! I take it your small solar inverters are “grid tied” and the “grid” is generated by the Chinese inverter

[rstevens81]

I did have a thought if you can set the timings of the 50hz sine wave you could get real 3 phase with 3 of them

[johu]

Some 1-phase inverters (e.g. SMA Sunny Island) support a sync-pulse to achieve just that. Chinese 75€ inverter - probably not

[Arkangl67]

Any chance there is a 120v north American version?
Great work, its really inspiring.

[johu]

I'm pretty sure there is. In fact the control module has solder jumpers where you can set 50/60 Hz and output voltage. Never touched them though.

[Ev8]

Mine arrived today I think I make have to get my hands on a 3D printed chademo plug and make it external, Did you bypass the rectifying diodes on the logic power supply? What where the specs of the isolated dc converter you used?

[johu]

Didn't bypass them, it takes very little power. Converter is 15V 200mA left over from gate driver

[Ev8]

Awesome thanks!

[Iceman96]

Great to see someone tackle this topic so please keep up the good work. I am a little bit concerned about your 3 phase to 1 phase plug though. iI know that you are aware of the risk, but it has the potential for disaster if you were not around! Have you considered instead installing a 4 pole changeover switch which you could then wire to a dedicated plug for the car? That way you could put the short in at the changeover switch and remove the risk of someone plugging you shorting lead in while the grid c/b was still closed. Also I can see how this would work ok when you have a small solar system ( minimal risk of the car ever getting to 100% SOC), but I dont think it would work for me, as I have an 8KW solar sytem, and it is not unusual for me to export 40kwh to the grid on a summer day here in Australia. Doyou know what would happen if I tried something like this here? Would my solar inverter just ramp down to just supply my house load? Or would the smoke escape somewhere?

[johu]

I only used this once for demonstration and maybe would use it again in the very unlikely event of a power outage.
Well if someone plugs in the shorted CEE plug it will just throw the breakers

With 8 kW it is indeed difficult to keep the battery from overcharging. Somehow you'd need to tell your solar inverter to throttle because the Chinese inverter won't throttle. If the V2H inverter is turned off your solar inverters anti-islanding will detect this and shut down as well. If you don't do anything about it you might set your battery on fire. And of course since the V2H inverter is rated "Chinese" 3 kW you'd need to limit the charge rate to that anyway.

[Iceman96]

Good to hear. My Fronius inverter has “export limits” that are configurable. As it would be seeing my car as “the grid” i could try to get the car to keep lowering the export limit I guess

[Swing]

The link is not working anymore.

But speaking of Chinese Inverters, there are a lot of Solar Hybrid Inverters like Deye suitable for high voltage.
They are somewhat bulky, and have more features than you will use in the car.
But they do it all, and can be controlled i.e. by Modbus / CAN bus.
If I get my van working, I will use one of those inverters.

It reliably gives and takes 3 phase power up to 25kW, or even higher but then they become really heavy.
I think it is a no go for any small EV, but once you have some space it might be great.
Since it can also double as the charger, although it must have 3 phase input.